A:to be discussed
B:to being discussed
C:to discu
D:to discussing
与铵根离子(NH 4+ )具有相同的质子数和电子数的微粒是( )
设U=R,集合A={x|﹣2<x<1},B={x|﹣1<x≤4},则如图中阴影部分表示的集合为____.